1. Field of the Invention
The present invention relates to a package molding jig, a method of manufacturing the package molding jig and a manufacturing apparatus for the package molding jig for use in a method of manufacturing an optical semiconductor device and in fabrication of the optical semiconductor device.
2. Description of the Related Art
In the related art, attempts have been undertaken to provide packages for optical semiconductor devices, such as LEDs, formed by casting or transfer molding using thermoplastic resin composed of main component such as epoxy resin.
Among such optical semiconductor devices, it has been a usual practice for round (shell-shaped) type LED lamps, for use in various applications such as information display plates and stop lamps of automotive vehicles, to be manufactured such that an optical semiconductor element (light-emitting element) is connected to and secured onto a distal end of a lead portion of a lead frame upon which the light-emitting element and a distal end of an adjacent lead portion are electrically connected by wire bonding upon which epoxy resin with a translucency is filled by casting for thereby forming a package in a given shape. This casting is a method of forming a lens portion with the use of a die made of resin and suited for manufacturing the round type LED lamps in a wide variety of lens shapes.
A die used for casting such epoxy resin, that is, a package molding jig, is generally manufactured by injection molding in a process separate from a manufacturing process of the above-described semiconductor device using polymethylpentene (Trademark: TPX) among thermoplastic resins.
Further, the casting of epoxy resin with the use of the package molding jig is carried out after the light-emitting element is connected by wire bonding upon which epoxy resin is filled in the package molding jig and a distal end, mounted with the light-emitting element, of the lead frame is immersed in the package molding jig in a given depth. Subsequently, in order to harden epoxy resin, the package molding jig is placed in a high temperature curing furnace at temperatures of 100 to 140° C. and heat is applied to the package molding jig for hardening.
After epoxy resin has been hardened, the package molding jig is removed from the lead frame subsequent to package molding, obtaining a round type LED lamp with a given shape. Subsequently, the lead frame is processed in a given shape and subjected to electrical tests and products accepted in tests are packaged for delivery.
Further, the package molding jig, for use in package molding implemented by above-described casting method, is repeatedly used for 20 to 30 times, which vary depending on the lens shapes to be subjected to casting, and then discarded.
Such a related art casting jig is disclosed in, for instance, Japanese Patent Provisional Publication No. 7-183440.
As mentioned above, during casting in the manufacturing process of the related art round type LED lamp, use is made of the package molding jig that is manufactured by injection molding thermoplastic resin as raw material. Since the package molding jig plays a role as a molding die for a lens shape of the round type LED lamp and the round type LED lamps to be manufactured have great variety of lens shapes, there is a need for package molding jigs to be prepared in conformity with the lens shapes of the round type LED lamps to be manufactured. Accordingly, in order to fabricate such package molding jigs by injection molding, a large number of injection molding dies conformed to the lens shapes must be manufactured with the resultant increase in labor hours and expenses in the fabrication. Also, a space is required for storage of such injection molding dies.
Further, the manufactured package molding jigs result in an increase in costs because of increased costs in fabrication and, hence, when manufacturing the round type LED lamps in view of cost reduction, one package molding jig needs to be used for 20 to 30 times. Therefore, it is required for reserving a place for storage of the large number of package molding jigs depending on the lens shapes of the round type LED lamps to be manufactured. In addition to this, since polymethylpentene, conventionally used in the package molding jig as raw material, is crystalline resin, contraction occurs due to crystallization each time a thermal history is applied, resulting in variation in dimensional precision. Therefore, the dimensional precision of the package molding jig differs in value at the first time when the package molding jig is used for manufacturing the round type LED lamp and at twentieth time when the package molding jig is used for manufacturing the round type LED lamp. Thus, variations occur in the lens shape of the manufactured round type LED lamp and the position of the light-emitting element in the round type LED lamp, causing the occurrence of fears in a difficulty of maintaining a product quality in a stable fashion.
In addition, during the related art round type LED lamp manufacturing process, the casting is carried out and a curing process (hardening process) is implemented to allow epoxy resin (sealing resin), which serves as a package, to be hardened upon which the package molding jig is removed and, thereafter, the lead frame is subjected to post-processes such as processing step and inspection step. During such post-processes or during handling operations subsequent to the post-processes, there are probabilities wherein lens portions of products are carelessly damaged, causing the occurrence of defective products.